disco
Daddy Dave
flood is right lol feel like I'm at gun fight with a knife
340 Build
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disco
Daddy Dave
I'm decent with a stick but I expect to screw up here and there, headers are fender well from hooker I'd like to think there ok!
disco
Daddy Dave
mderoy340
Well-Known Member
Tune what you have. Proper ignition curve and dialed in carb will wake up your motor. A 26" tire will help the rpms at the track. Learn to cut a light and you can win a lot of rounds. Once you get the most out of your current combo you can evaluate the data collected.
disco
Daddy Dave
this is revised with cam specs
PRH
Well-Known Member
Well, the cam looks about right for what you’re doing with the car.
It should make enough power to run 11’s, but it’s highly unlikely it will with 3.73’s and a stick.
Frankly, this is a case where a stroker crank would have been the best money you could have spent on the motor, from a “seat of the pants” bang-for-the-buck factor, when you were in the planning stages.
Even if it made zero more hp, the extra 75ft/lbs of tq, right where you’re using the motor most of the time, would put a big smile on your face.
What you built is a nice little pump gas 340 with a small cam....... and 340’s aren’t known for their awesome low end grunt.
I think it’s likely the motor is doing what it should....... and that you over estimated what that combination of parts would run like.
I’d seek out a chassis dyno at some point, make a few pulls just to insure nothing strange is going on with the fuel curve, and to see if the power numbers are somewhat close to what that combo should make.
I looked up the cam.
I see it’s a hydraulic...... for some reason I had it in my head it was a solid.
Another reason to get it on a dyno........ see where the valve float occurs, or if it will rev high enough to reach its natural peak before it gets into float.
Sometimes with a fast rate hyd cam things get unhappy and a lower rpm than you’d like.
I just had a mild 360 on the dyno last week with a little solid lifter cam.
That motor was making peak hp around 62-6300, and was still pulling strong to 6800.
Mid-5000’s is a pretty low point to peak for a 340 with decent heads on it.
My suspicion is, on an engine dyno, that combo would keep climbing until the lifters got unhappy.
It should make enough power to run 11’s, but it’s highly unlikely it will with 3.73’s and a stick.
Frankly, this is a case where a stroker crank would have been the best money you could have spent on the motor, from a “seat of the pants” bang-for-the-buck factor, when you were in the planning stages.
Even if it made zero more hp, the extra 75ft/lbs of tq, right where you’re using the motor most of the time, would put a big smile on your face.
What you built is a nice little pump gas 340 with a small cam....... and 340’s aren’t known for their awesome low end grunt.
I think it’s likely the motor is doing what it should....... and that you over estimated what that combination of parts would run like.
I’d seek out a chassis dyno at some point, make a few pulls just to insure nothing strange is going on with the fuel curve, and to see if the power numbers are somewhat close to what that combo should make.
I looked up the cam.
I see it’s a hydraulic...... for some reason I had it in my head it was a solid.
Another reason to get it on a dyno........ see where the valve float occurs, or if it will rev high enough to reach its natural peak before it gets into float.
Sometimes with a fast rate hyd cam things get unhappy and a lower rpm than you’d like.
I just had a mild 360 on the dyno last week with a little solid lifter cam.
That motor was making peak hp around 62-6300, and was still pulling strong to 6800.
Mid-5000’s is a pretty low point to peak for a 340 with decent heads on it.
My suspicion is, on an engine dyno, that combo would keep climbing until the lifters got unhappy.
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yellow rose
Overnight Sensation
Yup, ain't no way that's anywhere near 10:1 unless the chambers are 54 cc's and they are not. That's why I said you can't do the math from a catalog. You need to actually measure the stuff and THEN do the math. Catalogs, like people can be wrong. Or they just lie.
I'd almost promise you the cam isn't where the cam card calls for, and since you are down on CR (my guess is with that cam if I did the engine you be at a MEASURED 10.5-10.8:1 and it would still run on pump gas but I want to see all the numbers first) I'd bet you need to be at a minimum of 6 degrees advanced from the LSA. For a start. It may want more advance with the low CR and no gear.
yellow rose
Overnight Sensation
So now that I've seen the cam numbers, it's not as much cam as I run, but you'll still need a 4.30 gear with that tire. I run a 4.56 gear but I have a 26 inch tire and I run 255 @ .050
I would have talked you out of that hydraulic. Today's solids don't require .032 lash (none of them did but that's what they called for and yes it's stupid) and need to be checked every 5000 miles or so and that's if you beat on it.
You also need to verify the compression ratio and degree the cam. Never ever dot to dot a cam. Degreeing is so simple that once you learn it, you'll wonder why everyone doesn't do it. For way less than a hundred bucks you can buy all you need to do it.
I would have talked you out of that hydraulic. Today's solids don't require .032 lash (none of them did but that's what they called for and yes it's stupid) and need to be checked every 5000 miles or so and that's if you beat on it.
You also need to verify the compression ratio and degree the cam. Never ever dot to dot a cam. Degreeing is so simple that once you learn it, you'll wonder why everyone doesn't do it. For way less than a hundred bucks you can buy all you need to do it.
PRH
Well-Known Member
With zero deck, 5cc piston, 63cc head, 10cc gasket, 1cc area above rings...... I come up with 9.9:1.
Pretty close to 10:1.
Pretty close to 10:1.
nm9stheham
Well-Known Member
Yes.... same basic piston setup on a 340 and we have 10:1. Pistons measured at.004-.005" out of the hole. Cranking compression at 156-161 at 2400' elevation with a 212 @ 050" cam (intake). OP, if you would check the cranking compressions on all cylinders, that would help verify this.
The one question I have on the info leading to compression is if the pistons are really level with the deck as claimed..... Typical Icon pistons height sit about .010-.012" below nominal LA deck height.... lowers static CR by a couple of tenths. And with high deck height and a thick head gasket, SCR could be down close to 9.5..... but that is not going to be holding back the engine all that much at the top end.
IMHO, still not a good description from the OP as to what seems to be 'weak'. Boggy on the street or what? My son's 340 is very similar for heads, CR, and intake, with smaller cam, almost .100" less lift, Spitfire headers, and 600 cfm carb, 3.55 rear and 220 RPM stall TC on a 904 auto.... not the least bit boggy..... traction is the problem. Will spin tires at just over half throttle from a stop.
The one question I have on the info leading to compression is if the pistons are really level with the deck as claimed..... Typical Icon pistons height sit about .010-.012" below nominal LA deck height.... lowers static CR by a couple of tenths. And with high deck height and a thick head gasket, SCR could be down close to 9.5..... but that is not going to be holding back the engine all that much at the top end.
IMHO, still not a good description from the OP as to what seems to be 'weak'. Boggy on the street or what? My son's 340 is very similar for heads, CR, and intake, with smaller cam, almost .100" less lift, Spitfire headers, and 600 cfm carb, 3.55 rear and 220 RPM stall TC on a 904 auto.... not the least bit boggy..... traction is the problem. Will spin tires at just over half throttle from a stop.
I’d like to have a peak (so to speak) on the suspension & tire selection.
nm9stheham
Well-Known Member
I would not expect that operating RPM band with the .050" duration of 232*.
OP: do you have the original Edelbrock springs on the heads?
And I don't understand this statement: 'All in' as in how?
yellow rose
Overnight Sensation
yellow rose
Overnight Sensation
Should have read this first. Like I said, whole lotta if's in the OP's numbers.
Also, a converter is WAY more forgiving than a clutch is. You can be off on gear and the converter isn't as bothered by it.
Also, you most likely have better headers than the OP. There is almost no HP difference between two quality over the counter headers. But a junk set of headers is a power killer. May not be the OP's issue but those fender well headers are usually a power loser.
disco
Daddy Dave
Sorry when I called Dave Hughes he said with that cam my power would finished at 5400 rpm
disco
Daddy Dave
I've never degreed a cam before, but heard of it being done, does it make that much of a difference ?
disco
Daddy Dave
for the springs and lifters they came from Hughes engines and he custom made the pushrods
disco
Daddy Dave
The heads are a closed chamber 63 cc, according to Dave Hughes the Pistons in the 340 come out of the deck by 6 thou and with the icon Pistons he sold me in his words would be exactly 10-1 compression
PRH
Well-Known Member
I can’t see how a 232*@.050 cam would peak at 5400 in a 340 with rpm heads & manifold and headers........ unless there is something else holding it back........ like valvetrain stability.
Using the most basic airflow to cubic inch equation, an ootb rpm head flowing 240cfm has enough capacity to allow a 345” motor to peak at over 6600rpm(if everything else can keep up).
5400 seems really low to me.
The 360 I just tested had heads that flow less than ootb rpm heads, a manifold with less capacity than the an rpm, and a cam with way less lift than the OP’s cam.
The same formula shows the heads on the 360 flow enough to peak at just over 6k on that combo........ which is right about where it peaked.
Using the most basic airflow to cubic inch equation, an ootb rpm head flowing 240cfm has enough capacity to allow a 345” motor to peak at over 6600rpm(if everything else can keep up).
5400 seems really low to me.
The 360 I just tested had heads that flow less than ootb rpm heads, a manifold with less capacity than the an rpm, and a cam with way less lift than the OP’s cam.
The same formula shows the heads on the 360 flow enough to peak at just over 6k on that combo........ which is right about where it peaked.
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yellow rose
Overnight Sensation
It makes a difference if it's not installed correctly. You can have the key in the crank off a bit, the key in the cam off a bit, you can have the groove in the crank gear off a bit, you can have the groove in the cam gear off a bit or worse yet, some of all of it.
That's why the cam should always be degreed. That stuff is all made by humans and humans ain't perfect. The only way to KNOW where the cam is at is to degree it. A few degrees can make a big difference. Especially when you are short of gear like you are.
nm9stheham
Well-Known Member
Can you give us a model number on the Icon piston? That '6 thou out of the hole' number does not make sense so we can research it for you if we get a PN. Tnx.
The same goes for the springs PN; can you give us the Hughes PN on the valve springs? Telling us that they came from Hughes does not really tell anyone anything.
As above.... 'being done' at 5400 RPM is not making sense with this cam spec of 232 @ .050". PRH is IMHO saying one half : the top end RPM range is being cut off by the springs not being good enough to stay stable. This is a higher RPM cam.. not the highest range cam by any means but not 1500-5400. Do you have a Hughes PN for the cam?
And YR is going at the other possible half of the problem: This is not a small cam, and the low end RPM's are not going to start at 1500..... closer to 2800-ish IMHO. If you engage the clutch at an RPM range below that, then the engine is going to be sluggish/boggy until it gets revved up. The manual trans is unforgiving of a poor low RPM setup.
Several folks are really trying to help you, but something is not hanging together, and PN info will help.
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PRH
Well-Known Member
Like I said earlier, my guess is it’s running just fine....... and is just not what the OP was expecting.
If the cam is off a couple degrees, sure that would help if it was right..... same for the compression.
If it’s 9.5 instead of 10....... making it 10 would help....... but neither of those things is going to transform the motor into a totally different beast....... unless something is pretty far off.
As for the powerband..... for comparison:
340+.030, very mild bowl port 587’s w-2.02 intake(never flowed, but almost certainly less than 220cfm), std performer intake, Comp 268h([email protected]), 650dp carb, 1-5/8” headers....... peak tq@3800, peak hp@5200.
That’s with way less head, intake, and cam than the OP’s build.
If the valvetrain held on to say 6000-ish, I’d expect the OP’s build to get over 400hp.
If the cam is off a couple degrees, sure that would help if it was right..... same for the compression.
If it’s 9.5 instead of 10....... making it 10 would help....... but neither of those things is going to transform the motor into a totally different beast....... unless something is pretty far off.
As for the powerband..... for comparison:
340+.030, very mild bowl port 587’s w-2.02 intake(never flowed, but almost certainly less than 220cfm), std performer intake, Comp 268h([email protected]), 650dp carb, 1-5/8” headers....... peak tq@3800, peak hp@5200.
That’s with way less head, intake, and cam than the OP’s build.
If the valvetrain held on to say 6000-ish, I’d expect the OP’s build to get over 400hp.
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disco
Daddy Dave
I will get some numbers for you, it's very cool watching you people help out, there are some clever individuales on here. Thank you very much.
disco
Daddy Dave
Thank you
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